You would do well to listen more to your brother because he is right: turtles have the ability to breathe through their butt. Turtles primarily breathe through their mouth, sucking air into their lungs in a manner that is similar to how we breathe. However, in emergencies when not enough air can be breathed through the normal method, turtles can draw air into their butt where it reaches special glands that extract the oxygen and get it into the bloodstream.

Turtles are among the oldest living vertebrates on the planet. They have an ancestry that dates back 200 million years. The most prominent feature of turtles is their shell. Because it is rigid, it doesn’t allow for their chest and lungs to expand like that of most other animals that breathe through lungs. They have to squeeze their body against one side or another inside the shell to make room for air.

Because turtles live in the water, situations can often arise when they cannot get as much air as they need. Many water-dwelling species have special adaptations that allow them to get oxygen into their bloodstream through other means. This allows them to stay underwater for long periods of time.

Turtles have what is called a cloaca. This is a pouch or chamber at their rear end that contains both the exit of their digestive system and their sex organs. Turtles also have two small sacs, called bursae, in their cloaca. As turtles swim, water streams through the sacs and collects oxygen.

Inside the sacs are many small blood vessels that then carry the oxygen into the bloodstream. When turtles are out of the water, the cloaca remains open and the sacs collect oxygen out of the air. It is estimated that sometimes the bursa can account for over 65 percent of the turtle’s oxygen intake.

Butt-breathing, scientifically known as cloacal respiration, is not only limited to turtles. Other animals that breathe through their butt include sea cucumbers and dragonfly nymphs. Dragonfly nymphs are especially interesting because they can also shoot air out their butt as a means of jet propulsion when they need to move fast.